1. Field of Invention
The present invention relates to a driving circuit system for use in an active-matrix-type electro-optical device and for driving the electro-optical device, and also to an electro-optical device driven by this driving circuit system.
2. Description of Related Art
Generally, in an active matrix type electro-optical device, a plurality of scanning lines and a plurality of data lines are arranged in a matrix, and pixel electrodes are formed via switching elements, such as thin film diodes (hereinafter referred to as xe2x80x9cTFDsxe2x80x9d) and thin film transistors (hereinafter referred to as xe2x80x9cTFTsxe2x80x9d) in correspondence with the intersections of the matrix.
In the electro-optical device configured as described above, scanning signals are sequentially supplied to the respective scanning lines by a scanning-line driving circuit. More specifically, the scanning-line driving circuit has a Y-direction shift register formed of unit circuits in multiple stages in the Y direction (vertical direction), which is the direction in which the scanning lines are arranged. First, the Y-direction shift register sequentially transfers a start pulse, which is supplied from an external image signal processing circuit at the start of a vertical scanning period, based on the period of a Y-direction clock signal CLY (and its inverted signal CLYxe2x80x2), which is used as the reference of vertical scanning, output from the external image signal processing circuit. The Y-direction shift register then supplies transfer signals as scanning signals from the respective stages of the unit circuits to the corresponding scanning lines.
Meanwhile, the data lines are driven by a data-line driving circuit. That is, the data-line driving circuit is configured to supply sampling control signals to sampling switches, which sample an image signal supplied to an image signal line in correspondence with the individual data lines, in synchronization with the above-described operation of sequentially supplying scanning signals. More specifically, the data-line driving circuit has a multiple-stage X-direction shift register in the X direction (horizontal direction), which is the direction in which the data lines are arranged. First, the X-direction shift register sequentially transfers a start pulse, which is supplied from the external image signal processing circuit at the start of a horizontal scanning period, based on the period of an X-direction clock signal CLX (and its inverted signal CLXxe2x80x2), which is used as the reference of horizontal scanning, output from the image signal processing circuit. The X-direction shift register then outputs transfer signals as sampling control signals from the respective stages of the unit circuits to the sampling switches connected to the corresponding data lines. Subsequently, the sampling switches respectively sample the image signal supplied to the image signal line according to the sampling control signals and supply the sampled image signal to the corresponding data lines.
As discussed above, generally, in the active-matrix-type electro-optical device, vertical scanning based on a field unit or a frame unit, namely, field scanning or frame scanning, is performed in accordance with the scanning signals and sampling control signals sequentially output from the shift registers.
When being put into practical use, this type of electro-optical device often has a built-in driving circuit system in which the aforementioned scanning-line driving circuit and the data-line driving circuit are formed, together with the switching elements connected to the pixel electrodes, on one of a pair of substrates forming the electro-optical device. In this case, a small space occupied by peripheral circuits including the driving circuits makes it possible to miniaturize the entire device. Additionally, active elements, which form the peripheral circuits, are formed by the same process step as the switching elements for driving the pixel electrodes, thereby enhancing the manufacturing efficiency of the whole device and decreasing the cost.
The size of the substrates is a factor that defines the size of the entire electro-optical device. Accordingly, the formation of a large peripheral portion on which the scanning-line driving circuit and the data-line driving circuit are formed in the peripheral region on the substrates, in relation to a screen display portion, contradicts the basic demand in this technical field for miniaturizing the entire electro-optical device and increasing relatively the screen display portion in relation to the size of the electro-optical device.
Thus, for the formation of the driving circuits on the substrate, in the Y-direction shift register of the scanning-line driving circuit, the circuit pitch in the Y direction of each unit circuit (hereinafter simply referred to as the xe2x80x9ccircuit pitch of the Y-direction shift registerxe2x80x9d) is adjusted to the same pitch as that of the scanning lines. Accordingly, the Y-direction width of the portion required for forming the scanning-line driving circuit can be set to be substantially equal to the Y-direction width of the screen display portion. Similarly, in the X-direction shift register of the data-line driving circuit, the circuit pitch in the X direction of each unit circuit (hereinafter simply referred to as the xe2x80x9ccircuit pitch of the X-direction shift registerxe2x80x9d) and the pitch in the X direction of the sampling switches of the sampling circuit (hereinafter simply referred to as the xe2x80x9cpitch of the sampling switchxe2x80x9d) are adjusted to be the same pitch as that of the data lines. Accordingly, the X-direction width of the portion required for forming the data-line driving circuit can be set to be substantially equal to the X-direction width of the screen display portion. This makes it possible to reduce the widths in the X direction and in the Y direction of the substrates, thereby preventing a large scale of substrates.
These days, there is an intense demand for a higher level of image quality in the electro-optical device. In order to implement higher-definition images, it is thus necessary to reduce the pixel pitch to a very small size and also to driving a greater number of scanning lines and data lines at a higher frequency.
However, each unit circuit of the above-described shift registers is provided with a plurality of relatively complicated active elements. For example, each unit circuit requires at least three clocked inverters, each formed of four TFTs, positive and negative power sources for each clocked inverter, and wiring patterns for supplying a clock signal and its inverted signal. Accordingly, in the configuration in which peripheral circuits, such as the driving circuits, are formed on the substrate of the electro-optical device, as the pixel pitch is becoming smaller, it is more difficult to adjust the circuit pitches of the above-described Y-direction and X-direction shift registers to the same pitches of the scanning lines and the data lines. For example, under current circumstances, the smallest-possible circuit pitch of the shift registers is, in a practical sense, about 20 xcexcm, which hampers a decrease in the pixel pitch.
Accordingly, in view of the above background, the present invention provides a driving circuit system for use in an electro-optical device, which can cope with a decreased pixel pitch by using a relatively simple configuration, and also provides an electro-optical device integrating the above type of driving circuit system therein.
A first driving circuit system for use in an electro-optical device according to the present invention is a driving circuit system for use in an electro-optical device for driving pixels, the electro-optical device including switching elements and pixel electrodes connected to the switching elements. The switching elements are disposed in correspondence with intersections of a plurality of scanning lines and a plurality of data lines. The driving circuit system comprises a shift register, formed of a number of stages of unit circuits smaller than the number of the scanning lines, for sequentially outputting a transfer signal from each of the unit circuits based on a clock signal having a predetermined period, and an output circuit that divides the transfer signal output from each of the unit circuits into a plurality of transfer signal components in the time domain, and that sequentially outputs the transfer signal components as scanning signals to the scanning lines.
In the first driving circuit system for use in the electro-optical device according to the present invention, first of all, a transfer signal is sequentially output from each of the unit circuits forming the shift register. The transfer signal is then divided into a plurality of transfer signal components in the time domain by the output circuit, and the transfer signal components are output sequentially to the plurality of scanning lines as scanning signals. Accordingly, with a view to reducing the pixel pitch to a very small size, the circuit pitch of the shift register in relation to the pitch of the scanning lines can be increased in accordance with the number of transfer signal components divided by the output circuit.
For example, conventionally, if the total number of scanning lines is determined to be m (m is an integer, which is two or greater), at least the same m number of unit circuits forming the shift register are required. In contrast, according to the present invention, if the number of transfer signal components divided by the output circuit is n (n is an integer, which is two or greater), only m/n number of unit circuits forming the shift register are required, thereby reducing to 1/n of that of a known art. It is thus possible to increase the circuit pitch of the Y-direction shift register by n times. Additionally, in the present invention, the driving frequency of the shift register can be decreased in accordance with the above-described number n, thereby making it possible to suppress power consumption.
Meanwhile, it is sufficient that the output circuit is configured to divide the transfer signal in the time domain. Thus, the configuration of the output circuit can be made simpler than that of the unit circuits of the shift register. It is thus easy to form the Y-direction circuit pitch required for forming the output circuit smaller than the circuit pitch of the shift register.
According to one aspect of the aforementioned first driving circuit system for use in the electro-optical device, the output circuit may comprise a branching wiring, provided in correspondence with each of the unit circuits, for branching the transfer signal output from the corresponding unit circuit into the plurality of transfer signal components, and an enable circuit, provided in correspondence with each of the transfer signal components branched by the branching wiring, for outputting as the scanning signal an AND signal of each of the transfer signal components and a predetermined enable signal. The enable signals whose active periods do not overlap with each other may be supplied to the enable circuits to which the transfer signal components branched by the same branching wiring are supplied. According to this aspect, each of the transfer signals output from the shift register is branched by each of the plurality of branching wiring patterns. Then, an AND signal of the branched transfer signal component and the enable clock signal is obtained by the corresponding enable circuit, and is supplied to the corresponding scanning line as a scanning signal. Thus, the output circuit can be implemented by a comparatively simple circuit configuration, such as the branching wiring patterns and the enable circuits, thereby easily decreasing the circuit pitch of the output circuit. Hence, the circuit pitch of the enable circuit can be prevented from hampering a decrease in the pixel pitch.
According to the aspect in which the output circuit is provided with the enable circuits, among the enable circuits, the circuits adjacent to the scanning lines may be displaced from each other in the direction in which the data lines are arranged. With this arrangement, the adjacent enable circuits are displaced in the direction in which the scanning lines are arranged (namely, in the direction orthogonal to the direction in which the data lines are formed). Accordingly, the circuit elements forming each enable circuit can be formed with a greater width in the direction in which the scanning lines are arranged compared to the arrangement in which the adjacent enable circuits are aligned alternately along the direction in which the data lines are arranged (namely, linearly along with the direction in which the data lines are arranged). As a result, the circuit pitch of the enable circuits can be further decreased, thereby enhancing a smaller size of the pitch of the scanning lines:
According to the aspect in which the output circuit is provided with the enable circuits, each of the enable circuits may be formed by connecting in series a NAND gate for inputting the transfer signal component and the predetermined enable signal therein, and an inverter for inverting the output of the NAND gate. With this configuration, by using the NAND gate and the inverter connected in series, an AND signal of each of the branched transfer signal component and the enable signal can be reliably output with high precision. Additionally, the configuration of the NAND gate and the inverter is simpler than that of each of the unit circuits of the shift resistor. It is thus relatively easy to decrease the circuit pitch of the enable circuits.
According to the aspect in which the output circuit is provided with the enable circuits, each of the enable circuits may be formed of a transmission gate for outputting the scanning signal when the transfer signal component and the predetermined enable signal are input. With this configuration, since the transmission gate is a relatively simple circuit, the circuit pitch of the enable circuit can be relatively easily decreased. Additionally, the delay time required for generating the scanning signals from the transfer signal components can be decreased.
Alternatively, according to the aspect in which the output circuit is provided with the enable circuits, each of the enable circuits may be formed of a P-channel type or N-channel type thin film transistor for outputting the scanning signal when the transfer signal component and the predetermined enable signal are input. With this configuration, by using a P-channel type or N-channel type thin film transistor, the size of the enable circuit can be made relatively small. It is thus relatively easy to reduce the circuit pitch of the enable circuit. Additionally, since the number of transistors can be made comparatively small, the delay time required for generating the scanning signals from the transfer signal components can be decreased.
According to another aspect of the aforementioned first driving circuit system for use in the electro-optical device, the driving circuit system may be formed at both sides across a portion in which the pixel electrodes are formed, and one of the driving circuit systems may output the scanning signals to the odd-numbered scanning lines, while the other driving circuit system may output the scanning signals to the even-numbered scanning lines. According to this aspect, one of the divided driving circuit systems supplies the scanning signals to the odd-numbered scanning lines, while the other divided driving circuit system supplies the scanning signals to the even-numbered scanning lines. Accordingly, the circuit pitch of the shift register can be doubled. It is thus possible to further reduce the pitch of the scanning lines, in combination with the increased circuit pitch of the shift register in accordance with the number of transfer signal components divided by the output circuit.
An electro-optical device is driven by the above-described first driving circuit system for use in an electro-optical device. According to the electro-optical device, in particular, a decreased pitch of the scanning lines can be achieved by a relatively simple circuit configuration. As the electro-optical device, devices using various electro-optical materials between substrates, such as a liquid crystal device or an EL (Electro Luminescent) device, may be employed.
A second driving circuit system for use in an electro-optical device according to the present invention is a driving circuit system for use in an electro-optical device for driving pixels, the electro-optical device including switching elements and pixel electrodes connected to the switching elements. The switching elements are disposed in correspondence with intersections of a plurality of scanning lines and a plurality of data lines. The driving circuit system comprises a shift register, formed of a number of stages of unit circuits smaller than the number of the data lines, for sequentially outputting a transfer signal from each of the unit circuits based on a clock signal having a predetermined period, an output circuit for dividing the transfer signal output from each of the unit circuits into a plurality of transfer signal components in the time domain, and for outputting the transfer signal components as sampling control signals, and a sampling switch, provided in correspondence with each of the data lines, for sampling an image signal according to the sampling control signals divided by the output circuit, and for supplying the image signal to the corresponding data line.
In the second driving circuit system for use in the electro-optical device according to the present invention, first of all, a transfer signal is sequentially output from each of the unit circuits forming the shift register. The transfer signal is then divided into a plurality of transfer signal components in the time domain by the output circuit, and the transfer signal components are sequentially output to the sampling switches as sampling control signals. Accordingly, with a view to reducing the pixel pitch to a very small size, the circuit pitch of the shift register in relation to the pitch of the data lines can be increased in accordance with the number of transfer signal components divided by the output circuit.
For example, conventionally, if the total number of data lines is determined to be p (p is an integer, which is two or greater), at least the same p number of unit circuits forming the shift register are required. In contrast, according to the present invention, if the number of transfer signal components divided by the output circuit is q (q is an integer, which is two or greater), only p/q number of unit circuits forming the shift register are required, thereby reducing to 1/q of that of a known art. It is thus possible to increase the circuit pitch of the X-direction shift register by q times. Additionally, in the present invention, the driving frequency of the shift register can be decreased in accordance with the above-described number q, thereby making it possible to suppress power consumption. This effect is more noticeable in the data-line driving circuit than the scanning-line driving circuit, since the operating frequency of the data-line driving circuit is much higher than that of the scanning-line driving circuit. Meanwhile, it is sufficient that the output circuit is configured to divide the transfer signal in the time domain. Thus, the configuration of the output circuit can be made simpler than that of the unit circuits of the shift register. It is thus easy to form the X-direction circuit pitch required for forming the output circuit smaller than the circuit pitch of the shift register.
According to one aspect of the second driving circuit system for use in the electro-optical device, the output circuit may comprise a branching wiring, provided in correspondence with each of the unit circuits, for branching the transfer signal output from the corresponding unit circuit into the plurality of transfer signal components, and an enable circuit, provided in correspondence with each of the transfer signal components branched by the branching wiring, for outputting as the sampling control signal an AND signal of each of the transfer signal components and a predetermined enable signal. The enable signals whose active periods do not overlap with each other may be individually supplied to the enable circuits to which the transfer signal components branched by the same branching wiring pattern are supplied. According to this aspect, each of the transfer signals output from the shift register is branched by each of the plurality of branching wiring patterns. Then, an AND signal of the branched transfer signal component and the enable clock signal is obtained by the corresponding enable circuit, and is supplied to the corresponding sampling switch as a sampling control signal. Thus, the output circuit can be implemented by a comparatively simple circuit configuration, such as the branching wiring patterns and the enable circuits, thereby easily decreasing the circuit pitch of the output circuit. Hence, the circuit pitch of the enable circuit can be prevented from hampering a decrease in the pixel pitch.
According to one aspect of the output circuit provided with the enable circuits, each of the enable circuits may be formed by connecting in series a NAND gate for inputting the transfer signal component and the predetermined enable signal therein, and an inverter for inverting the output of the NAND gate. With this configuration, by using the NAND gate and the inverter connected in series, an AND signal of each of the branched transfer signal component and the enable signal can be reliably output with high precision. Additionally, the configuration of the NAND gate and the inverter is simpler than that of each of the unit circuits constituting each stage of shift resistor. It is thus relatively easy to decrease the circuit pitch of the enable circuits.
According to another aspect of the output circuit provided with the enable circuits, each of the enable circuits may be formed of a transmission gate for outputting the sampling control signal when the transfer signal component and the predetermined enable signal are input. With this configuration, since the transmission gate is a relatively simple circuit, the circuit pitch of the enable circuit can be relatively easily decreased. Additionally, the delay time required for generating the sampling control signals from the transfer signal components can be decreased.
An electro-optical device is driven by the above-described second driving circuit system for use in an electro-optical device. According to the electro-optical device, in particular, a decreased pitch of the data lines can be achieved by a relatively simple circuit configuration. As the electro-optical device, devices using various electro-optical materials between substrates, such as a liquid crystal device or an EL device, may be employed.
A third driving circuit system for use in an electro-optical device according to the present invention is a driving circuit system for use in an electro-optical device including switching elements disposed in correspondence with intersections of a plurality of scanning lines and a plurality of data lines, and pixel electrodes connected to the switching elements. The electro-optical device simultaneously samples serial-parallel converted image signals onto a predetermined number of data lines. The driving circuit system comprises a shift register, formed of a number of stages of unit circuits smaller than the number of data lines onto which the image signals are simultaneously sampled, for sequentially outputting a transfer signal from each of the unit circuits based on a clock signal having a predetermined period, an output circuit for dividing the transfer signal output from each of the unit circuits into a plurality of transfer signal components in the time domain, and for outputting the transfer signal components as sampling control signals, and a sampling switch, provided in correspondence with each of the data lines, for sampling one of the image signals according to the corresponding sampling control signal, and for supplying the image signal to the corresponding data line. The sampling switches provided in correspondence with a plurality of adjacent data lines simultaneously sample the different image signals according to the same sampling control signal.
In the third driving circuit system for use in the electro-optical device according to the present invention, first of all, a transfer signal is sequentially output from each of the unit circuits of the shift register. The transfer signal is then divided into a plurality of transfer signal components in the time domain by the output circuit, and the transfer signal components are sequentially output to the sampling switches as sampling control signals. In this case, the sampling switches provided in correspondence with a plurality of adjacent data lines simultaneously sample the different image signals according to the same sampling control signal. Consequently, with a view to reducing the pixel pitch to a very small size, the circuit pitch of the shift register in relation to the pitch of the data lines can be increased in accordance with the number of transfer signal components divided by the output circuit and the number of simultaneously driven sampling switches.
For example, conventionally, if the total number of data lines is determined to be p (p is an integer, which is two or greater), at least the same p number of unit circuits forming the shift register are required. In contrast, according to the present invention, if the number of transfer signal components divided by the output circuit is q (q is an integer, which is two or greater), and if the number of simultaneously driven sampling switches is determined to be r (r is an integer, which is two or greater), only p/(qxc3x97r) number of unit circuits forming the shift register are required, thereby reducing to 1/(qxc3x97r) of that of a known art. It is thus possible to increase the circuit pitch of the X-direction shift register by qxc3x97r times. Additionally, in the present invention, the driving frequency of the shift register can be decreased in accordance with the number of transfer signal components divided by the output circuit and the number of simultaneously driven sampling switches, thereby making it possible to suppress power consumption and also to increase the life of the circuit. This effect is more noticeable in the data-line driving circuit than the scanning-line driving circuit, since the operating frequency of the data-line driving-circuit is much higher than that of the scanning-line driving circuit. Meanwhile, it is sufficient that the output circuit is configured to divide the transfer signal in the time domain. Thus, the configuration of the output circuit can be made simpler than that of the unit circuits of the shift register. It is thus easy to form the X-direction circuit pitch required for forming the output circuit smaller than the circuit pitch of the shift register.
According to one aspect of the aforementioned third driving circuit system for use in the electro-optical device, the output circuit may comprise a branching wiring pattern, provided in correspondence with each of the unit circuits, for branching the transfer signal output from the corresponding unit circuit into the plurality of transfer signal components, and an enable circuit, provided in correspondence with each of the transfer signal components branched by the branching wiring pattern, for outputting as the sampling control signal an AND signal of each of the transfer signal components and a predetermined enable signal. The enable signals whose active periods do not overlap with each other may be individually supplied to the enable circuits to which the transfer signal components branched by the same branching wiring pattern are supplied. According to this aspect, each of the transfer signals output from the shift register is branched by each of the plurality of branching wiring patterns. Then, AND signals of the branched transfer signal components and the enable clock signals are obtained by the corresponding enable circuits, and are supplied to the corresponding number of sampling switches as sampling control signals. Thus, the output circuit can be implemented by a comparatively simple circuit configuration, such as the branching wiring patterns and the enable circuits, thereby easily decreasing the circuit pitch of the output circuit. Hence, the circuit pitch of the enable circuit can be prevented from hampering a decrease in the pixel pitch.
According to one aspect of the output circuit provided with the enable circuits, each of the enable circuits may be formed by connecting in series a NAND gate for inputting the transfer signal component and the predetermined enable signal therein, and an inverter for inverting the output of the NAND gate. With this configuration, by using the NAND gate and the inverter connected in series, an AND signal of each of the branched transfer signal component and the enable signal can be reliably output with high precision. Additionally, the configuration of the NAND gate and the inverter is simpler than that of each of the unit circuits forming the shift register. It is thus relatively easy to decrease the circuit pitch of the enable circuits.
According to another aspect of the output circuit provided with the enable circuits, each of the enable circuits may be formed of a transmission gate for outputting the sampling control signal when the transfer signal component and the predetermined enable signal are input. With this configuration, since the transmission gate is a relatively simple circuit, the circuit pitch of the enable circuit can be relatively easily decreased. Additionally, the delay time required for generating the sampling control signals from the transfer signal components can be decreased.
An electro-optical device is driven by the above-described third driving circuit system for use in an electro-optical device. According to the electro-optical device, in particular, a decreased pitch of the data lines can be achieved by a relatively simple circuit configuration. As the electro-optical device, devices using various electro-optical materials between substrates, such as a liquid crystal device or an EL device, may be employed.
A fourth driving circuit system for use in an electro-optical device according to the present invention is a driving circuit system for use in an electro-optical device for driving pixels, the electro-optical device including switching elements and pixel electrodes connected to the switching elements. The switching elements are disposed in correspondence with intersections of a plurality of scanning lines and a plurality of data lines. The driving circuit system comprises a shift register, formed of a number of stages of unit circuits smaller than the number of the data lines, for sequentially outputting a transfer signal from each of the unit circuits based on a clock signal having a predetermined period, an output circuit for dividing the transfer signal output from each of the unit circuits into a plurality of transfer signal components in the time domain or simultaneously distributing the transfer signal into a plurality of transfer signal components, and for outputting the transfer signal components as sampling control signals, and a sampling switch, provided in correspondence with each of the data lines, for sampling an image signal supplied to one of a plurality of image signal lines according to the transfer signal components divided by or distributed by the output circuit, and for supplying the image signal to the corresponding data line.
In the fourth driving circuit system for use in the electro-optical device according to the present invention, first of all, a transfer signal is sequentially output from each of the unit circuits of the shift register. The transfer signal is then divided into a plurality of transfer signal components in the time domain or is simultaneously distributed into a plurality of transfer signal components by the output circuit, and the transfer signal components are output as sampling control signals. In this case, if the transfer signal is divided into a plurality of transfer signal components in the time domain by the output circuit, the individual sampling switches sequentially perform a sampling operation one-by-one. If the transfer signal is simultaneously distributed, the sampling switches provided in correspondence with a plurality of adjacent data lines simultaneously perform a sampling operation. Thus, what is called sequential driving and simultaneous-multiple driving can be switched by the output circuit. Further, in the present invention, the circuit pitch of the shift register in relation to the pitch of the data line can be increased in accordance with the number of transfer signal components divided by the output circuit. Additionally, in the present invention, the driving frequency of the shift register can be reduced to the reciprocal of the number of transfer signal components divided by the output circuit. Meanwhile, it is sufficient that the output circuit is configured to divide the transfer signal in the time domain or to simultaneously distribute the transfer signal. Accordingly, the configuration of the output circuit can be made simpler than that of the unit circuits of the shift register. It is thus easy to form the X-direction circuit pitch required for forming the output circuit smaller than the circuit pitch of the shift register.
According to one aspect of the aforementioned fourth driving circuit system for use in the electro-optical device, when the output circuit divides the transfer signal into the plurality of transfer signal components in the time domain, the same image signal may be supplied to the plurality of image signal lines, and each of the sampling switches may sequentially sample the image signal. When the output circuit simultaneously distributes the transfer signal into the plurality of transfer signal components, a single-type image signal may be expanded by a plurality of times in the time domain and may be distributed onto the plurality of image signal lines to the plurality of image signal lines. Among the sampling switches, the adjacent sampling switches provided in correspondence with a plurality of adjacent data lines may simultaneously sample the image signals. With this configuration, when the transfer signal is divided into a plurality of transfer signal components in the time domain, the same image signal is supplied to a plurality of image signal lines, thereby enabling sequential driving. When the transfer signal is simultaneously distributed into a plurality of transfer signal components, a single-type image signal is expanded to image signals by a plurality of times in the time domain, and the image signals are supplied to the plurality of image signal lines, thereby enabling simultaneous-multiple driving.
According to another aspect of the aforementioned fourth driving circuit system for use in the electro-optical device, the output circuit may comprise a branching wiring pattern, provided in correspondence with each of the unit circuits, for branching the transfer signal output from the corresponding unit circuit into the plurality of transfer signal components, and an enable circuit, provided in correspondence with each of the transfer signal components branched by the branching wiring pattern, for outputting as the sampling control signal an AND signal of each of the transfer signal components and a predetermined enable signal. When the transfer signal is divided into the plurality of transfer signal components in the time domain, the enable signals whose active periods do not overlap with each other during a cycle in which the transfer signal components branched by the same branching wiring pattern are supplied may be individually supplied to the enable circuits to which the transfer signal components branched by the same branching wiring pattern are supplied. When the transfer signal is simultaneously distributed into the transfer signal components, the enable signals whose active periods are in phase during a cycle in which the transfer signal components branched by the same branching wiring pattern are supplied may be individually supplied to the enable circuits to which the transfer signal components branched by the same branching wiring pattern are supplied. According to this aspect, each of the transfer signals output from the shift register is branched by the plurality of branching wiring patterns. An AND signal of the branched transfer signal component and an enable clock signal is obtained by the enable circuit, and is supplied to the corresponding sampling switch as a sampling control signal. Thus, since the output circuit can be implemented by a comparatively simple circuit configuration, such as the branching wiring pattern and the enable circuit, the circuit pitch of the output circuit can be easily reduced. Accordingly, the circuit pitch can be prevented from hampering a reduction in the pixel pitch.
In one aspect of the output circuit provided with the enable circuits, each of the enable circuits may be formed by connecting in series a NAND gate for inputting the transfer signal component and the predetermined enable signal therein, and an inverter for inverting the output of the NAND gate. With this configuration, by using the NAND gate and the inverter connected in series, the AND signal of the branched transfer signal component and the enable signal can be reliably output with high precision. Also, since the NAND gate and the inverter are simpler than the unit circuits of the shift register, the circuit pitch of the enable circuit can be relatively easily decreased.
In another aspect of the output circuit provided with the enable circuits, each of the enable circuits may be formed of a transmission gate for outputting the sampling control signal when the transfer signal component branched by the branching wiring pattern and the predetermined enable signal are input. With this configuration, since the transmission gate is relatively a simple circuit, it is comparatively easy to reduce the circuit pitch of the enable circuit. Additionally, the delay time required for generating the sampling control signal from the transfer signal can be shortened.
An electro-optical device is driven by the above-described fourth driving circuit system. According to the electro-optical device, in particular, a decreased pitch of the data lines can be achieved by a relatively simple circuit configuration. As the electro-optical device, devices using various electro-optical materials between substrates, such as a liquid crystal device or an EL device, may be employed.
According to one aspect of the electro-optical device, the electro-optical device may comprise determining means for making a determination of whether the transfer signal is divided into the plurality of transfer signal components in the time domain or is simultaneously distributed into the plurality of transfer signal components in the output circuit, and supplying means for individually supplying the enable signals whose active periods do not overlap with each other during a cycle in which the transfer signal components branched by the same branching wiring pattern are supplied to enable circuits to which the transfer signal components branched by the same branching wiring pattern are supplied when it is determined that the transfer signal is divided into the plurality of transfer signal components in the time domain. The supplying means individually supplies the enable signals whose active periods are in phase during a cycle in which the transfer signal components branched by the same branching wiring pattern are supplied to the enable circuits to which the transfer signal components branched by the same branching wiring pattern are supplied when it is determined that the transfer signal is simultaneously distributed into the plurality of transfer signal components. According to this aspect, the determining means determines whether sequential driving or simultaneous-multiple driving is employed, and the enable signal required for the determined type of driving is supplied to the enable circuit by the supplying means.
In one aspect of the electro-optical device provided with the determining means and the supplying means, the determining means may make the determination based on the type of the input image signal. For example, if the image signal is a video-type signal, such as an NTSC, PAL, or SECAM signal, the determining means determines that the transfer signal is to be divided into a plurality of transfer signal components in the time domain, thereby performing sequential driving. On the other hand, if the image signal is a data-type signal, such as a signal from a personal computer, the determining means determines that the transfer signal is simultaneously distributed into a plurality of transfer signal components, thereby performing simultaneous-multiple driving.
In another aspect of the electro-optical device provided with the determining means and the supplying means, the electro-optical device may further comprise a motion detector for detecting motion included in the input image signal and for outputting a detection signal. The determining means may determine that the transfer signal is to be divided into the plurality of transfer signal components in the time domain when it has determined, based on the detection signal, that the motion has been detected in the input image signal within a predetermined period. The determining means may determine that the transfer signal is to be simultaneously distributed into the plurality of transfer signal components when it has determined that the motion has not been detected in the input image signal within the predetermined period. According to this aspect, sequential driving and simultaneous-multiple driving are switched according to motion included in the image signal, thereby making it possible to drive the individual data lines. That is, sequential driving is performed on an image with rapid motion, resulting in the regularity of the image, while simultaneous-multiple driving is performed on an image with no (or less) motion, resulting in high-definition display. Thus, the optimal driving type in response to the characteristics of the image to be displayed can be selected to output the image.
A fifth driving circuit system for use in an electro-optical device according to the present invention is a driving circuit system for use in an electro-optical device for driving pixels, the electro-optical device including switching elements and pixel electrodes connected to the switching elements. The switching elements are disposed in correspondence with intersections of a plurality of scanning lines and a plurality of data lines. The driving circuit system comprises a shift register, formed of a number of stages of unit circuits smaller than the number of the data lines, for sequentially outputting a transfer signal from each of the unit circuits based on a clock signal having a predetermined period, a first output circuit for dividing the transfer signal output from each of the unit circuits into a plurality of transfer signal components in the time domain, a second output circuit for further dividing each of the transfer signal components divided by the first output circuit into a plurality of transfer signal portions in the time domain or simultaneously distributing each of the transfer signal components into a plurality of transfer signal portions, and for outputting the transfer signal portions as sampling control signals, and a sampling switch, provided in correspondence with each of the data lines, for sampling an image signal supplied to one of a plurality of image signal lines in accordance with the transfer signal portion divided or distributed by the second output circuit, and for supplying the image signal to the corresponding data line.
In the fifth driving circuit system for use in the electro-optical device according to the present invention, first of all, a transfer signal is sequentially output by each of the unit circuits of the shift register. The transfer signal is then divided into a plurality of transfer signal components in the time domain by the first output circuit. The divided transfer signal component is further divided into a plurality of transfer signal portions in the time domain or is simultaneously distributed into a plurality of transfer signal portions by the second output circuit, and the transfer signal portions are output as sampling control signals. Thus, with a view to reducing the pixel pitch to a very small size, the circuit pitch of the shift register in relation to the pitch of the data lines can be increased in accordance with the number of transfer signal components divided by the first output circuit and the number of transfer signal portions divided by the second output circuit.
For example, conventionally, if the total number of data lines is determined to be p (p is an integer, which is two or greater), at least the same p number of unit circuits forming the shift register are required. In contrast, according to the present invention, if the number of transfer signal components divided by the first output circuit is q (q is an integer, which is two or greater), and if the number of transfer signal portions divided by the second output circuit is s (s is an integer, which is two or greater), only p/(qxc3x97s) number of unit circuits forming the shift register are required, thereby reducing to 1/(qxc3x97s) of that of a known art. It is thus possible to increase the circuit pitch of the X-direction shift register by qxc3x97s times. Additionally, in the present invention, the driving frequency of the shift register can be decreased in accordance with the product of the number of transfer signal components and the number of transfer signal portions. This effect is more noticeable in the data-line driving circuit than the scanning-line driving circuit, since the operating frequency of the data-line driving circuit is much higher than that of the scanning-line driving circuit.
Meanwhile, it is sufficient that the first output circuit is configured to divide the transfer signal in the time domain and that the second output circuit is configured to divide the transfer signal component in the time domain or simultaneously distribute the transfer signal component. Thus, the configurations of the first output circuit and the second output circuit can be made simpler than that of the unit circuits of the shift register. It is thus easy to form the X-direction circuit pitch required for forming the first and second output circuits, in particular, the second output circuit, which correspond to the scanning lines, smaller than the circuit pitch of the shift register.
Further, in the present invention, when the second output circuit divides the transfer signal component into a plurality of transfer signal portions in the time domain, the individual sampling switches perform a sampling operation in turn one-by-one. When the second output circuit simultaneously distributes the transfer signal component, a plurality of sampling switches provided in correspondence with a plurality of adjacent data lines simultaneously perform a sampling operation. Consequently, what is called sequential driving and simultaneous-multiple driving can be switched by the second output circuit.
According to one aspect of the fifth driving circuit system for use in the electro-optical device, the first output circuit may comprise a first branching wiring pattern, provided in correspondence with each of the unit circuits, for branching the transfer signal output from the corresponding unit circuit into the plurality of transfer signal components, and a first enable circuit, provided in correspondence with each of the transfer signal components branched by the first branching wiring pattern, for outputting an AND signal of the transfer signal component branched by the first branching wiring pattern and an enable signal belonging to a first group. The enable signals belonging to the first group whose active periods do not overlap with each other during a cycle in which the transfer signal components branched by the same first branching wiring pattern are supplied are individually supplied to the first enable circuits to which the transfer signal components branched by the same first branching wiring pattern are supplied. The second output circuit may comprise a second branching wiring pattern, provided in correspondence with each of the first enable circuits, for branching each of the transfer signal components divided by the corresponding first enable circuit into the plurality of transfer signal portions, and a second enable circuit, provided in correspondence with each of the transfer signal portions branched by the second branching wiring pattern, for outputting as a sampling control signal an AND signal of the transfer signal portion branched by the second branching wiring pattern and an enable signal belonging to a second group. When the transfer signal component is divided into the plurality of transfer signal portions in the time domain, the enable signals belonging to the second group whose active periods do not overlap with each other during a cycle in which the transfer signal portions branched by the same second branching wiring pattern are supplied are individually supplied to the second enable circuits to which the transfer signal portions branched by the same second branching wiring pattern are supplied. When the transfer signal component is simultaneously distributed into the plurality of transfer signal portions, the enable signals belonging to the second group whose active periods are in phase during a cycle in which the transfer signal portions branched by the same second branching wiring pattern are supplied are individually supplied to the second enable circuits to which the transfer signal portions branched by the same second branching wiring pattern are supplied. According to this aspect, the transfer signal output from the shift register is first branched by each of a plurality of first branching wiring patterns, and an AND signal of the transfer signal component and an enable signal belonging to the first group is obtained by the first enable circuit. The AND signal is further branched by each of a plurality of second branching wiring patterns. An AND signal of the above AND signal and an enable signal belonging to the second group is obtained by the second enable circuit, and is supplied to the corresponding sampling switch as a sampling control signal. Accordingly, the first output circuit can be implemented by a relatively simple circuit configuration, such as the first branching wiring patterns and the first enable circuits. Similarly, the second output circuit can be implemented by a relatively simple circuit configuration, such as the second branching wiring patterns and the second enable circuits. Thus, the circuit pitches of the first and second output circuits can be easily decreased. As a consequence, the circuit pitches of the first and second output circuits can be prevented from hampering a decrease in the pixel pitch.
An electro-optical device is driven by the above-described fifth driving circuit system. According to the electro-optical device, in particular, a decreased pitch of the data lines can be achieved by a relatively simple circuit configuration. As the electro-optical device, devices using various electro-optical materials between substrates, such as a liquid crystal device or an EL device, may be employed.